Mn/Ce nano-composite oxides containing different amounts of manganese (5, 9, 17, 23, 29, 34 wt% as MnO2) were prepared by impregnation method at various calcination temperatures. Effect of both thermal treatment and loading on the structural, surface and microstructure properties of the as prepared nano-composites was determined. The combined effect of manganese oxide and ceria, at different concentrations, strongly influences the previous properties of the nano-composite oxides, by dispersing the MnO2 phase and promoting the efficiency of the Ce4+- Ce3+ and Mn4+ - Mn3+ redox couples.
The thermal treatment and loading influenced the interaction between manganese and CeO2 evidently. The incorporation of Mn ions into CeO2 crystal lattice resulted in weaker interaction between manganese and ceria on composite surface. Manganese loading at 400oC led to a slight increase in the ceria crystallite size which decreased by increasing the calcination temperature from 400 to 600oC. The sintering activation energy of ceria was evaluated to be 12kJ/mol for the MnO2/CeO2 nano-composite.